CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY [Abstract]
Foreign currency translation adjustment, tax effect	$ (648)	$ (194)	$ (219)
Unrealized holding gains (losses) on marketable securities, tax effect	(2)	5	90
Change in unfunded SERP liability, tax	$ 71	$ 2	$ (631)